hi, i have a renault megane 1.5dci expression 54 reg which ive recently bought second hand, after driving it home i noticed a fault come up saying injection fault and the stop light comes on, after about 10 seconds though this warning disappears, there was no drop in power at all so i thought nothing of it. then trying to start the engine up in the morning the engine turns over but nothing, it takes about 3 or 4 times sometimes even 6 but works eventually. I've had a look under the bonnet and noticed a bit of air in the fuel line which leads me to think the pump is faulty. when the engine is warm it'll start no problem but when its been sitting for a while it takes a while to start and comes up with the injection fault warning again. any ideas on what it maybe? and whether or not this problem is commom? oh and sometimes the injection fault comes up again over 3000 rpm but then it disappears. any answers or information would be gratefully received.